As is well known in the prior art, a skateboard typically includes an elongated board, sometimes referred to as a deck, having an upper surface and a lower surface. The upper surface supports the feet of the skateboard rider and the lower surface has two sets of trucks that are longitudinally spaced. Skateboard trucks have attached front and back sets of wheels that have the ability to both travel over an up and down range as well as pivot around a central point forward and aft. A central axle extends through the trucks and into the wheels which are rotatably attached to the ends of the trucks.
The rider stands on the upper surface of the board and by shifting the location of the feet and center of gravity, tilts the board to cause change of direction. Conventional skateboards require that a rider provide the propelling force to move, in the form of placing one of the rider's feet on the ground and pushing with that foot as the other foot remains on the top surface of the board. By virtue of the manual propulsion, a conventional skateboard has limitations in both speed as well as the fact that the rider can tire over a period of time. Perhaps it is for these reasons that conventional skateboards are typically used by adolescents and much less by adults.
A search of the prior art did not disclose any literature or patents that read directly on the claims of the instant invention. However, the following U.S. patents are considered related:
U.S. PAT. NO.INVENTORISSUED4,073,356Schlicht14 Feb. 19785,020,621Martin 4 Jun. 19915,487,441Endo et al30 Jan. 19965,893,425Finkle13 Apr. 19992004/0163867Hillman26 Aug. 20046,848,527Nelson 1 Feb. 20057,172,044Bouvet 6 Feb. 2007
U.S. Pat. No. 5,020,621 issued to Martin, U.S. Pat. No. 5,893,425 issued to Finkle, and U.S. publication 2004/0163867 issued to Hillman each disclose a motorized skateboard that mounts an engine or a motor at the rear end of the skateboard and utilizes a transmission to mechanically transmit rotary power from the motor to a wheel or wheels of a skateboard truck. While these attempts create propulsion for the skateboard, certain issues are created. When only turning a single wheel, the wheel turns on one side at a different speed than on the other side. Moreover, the wheels and trucks of conventional skateboards are able to pivot and move somewhat, as described previously. Designing and incorporating a transmission or differential between the motor and the skateboard wheel it adds cost and complexity to the device. Moreover, the skateboard cannot turn or move as it typically does, and thus the skateboard loses its “feel”, maneuverability and performance.
Yet other designs have incorporated a fifth wheel in roughly the center of the board. Examples of these include U.S. Pat. No. 4,073,356 issued to Schlicht, and U.S. Pat. No. 5,487,441 issued to Endo et al which disclose the use of a fifth driven wheel disposed intermediate the front and rear trucks or sets of wheels of the skateboard. These designs utilize an engine and battery which are also positioned mid-board. The driven fifth wheel in each case is rigidly, but rotatably, mounted to the skateboard. On non-even terrain, it may be difficult for the wheel to follow the terrain in a manner that can maintain traction with the ground so that there are no interruptions in propulsion of the skateboard. This also creates difficulties for traction if there are protrusions or bumps that the skateboard encounters.
Another disadvantage of the Schlicht arrangement is that a portion of the wheel as well as the motor and controls and the like are disposed on the upper surface of the board. U.S. Pat. No. 6,848,527 issued to Nelson also has such an arrangement. Of course, it should be appreciated by those skilled in the art that Nelson's design presents an impediment when the rider positions his feet or body.
Furthermore, positioning a fifth wheel between the trucks of the skateboard creates a completely different ride and feel than that of a conventional skateboard. U.S. Pat. No. 7,172,044 to Bouvet provides a non-motorized, self-propelled wheel board having a large wheel in the middle thereof, and describing the riding sensation as surfing on the ground.
Accordingly, there is a continuing need for a motorized skateboard which provides riding and maneuvering capabilities and characteristics which are identical, or nearly identical, to that of most conventional skateboards. The present invention fulfills these needs, and provides other related advantages as described below.